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04! $/3999 11:08 2098325152 WRIGHT .ENVIRONMENTAL. PAGE 87 <br /> parameters stabilize, which is interpreted to be aquifer water entering the casing. The sample <br /> will be carefully collected with a clean bailer and poured into the appropriate labcratory <br /> prepared container with minimum cavitation. The water sample will be labeled,logged onto a <br /> chain-of-custody farm, and placed at a chilled we chest. Upon completion of well s=p1mg, ' <br /> the well will be closed arta locked. <br /> Soil Covtamiivant Estimate Calculation w <br /> An estimate of corstan.ir=t mass was calculated using the available oformation from.prXvious <br /> studies. This work is related to interpreted soil contaminants in the immediate vicinity:of the ' <br /> former tank pit. The calculation of contaminant mass quantity ale w+ennal estittates otkM the <br /> numbers should be treated as a working numbers only. Calculations used methods and <br /> assumed figures from Lyman, Reidy, and levy. (1992)• Concentration data taken from the <br /> Wright Environmental Assessment Report (1995, see Table 1). Wright assumes the follswirg <br /> for the proposed excavation. Concentraton data taken .from the Wright Envirorunental <br /> Assessment Report (1995, see Table 1). Wright assumes the following for the pre-posed <br /> excavation: <br /> Azea=25' x 30' -,A sq. ft_ Overburden to a depth of 8.5 ft assumed clean. <br /> Thickness of contaminated area(i. e. capillary fringe)=4.5 feet <br /> Contaminated volume=750sq.ft.x 4.5 ft.=745.5 cu. ft or 27.9 cu..vds. <br /> Average soil concentrations -assumes 100% absorption to soil in pore spaces. <br /> TPHG= 110 ppm' Benzene-0.024 ppb#5tm of STEX =0.063 ppb* is <br /> Last quarterfy monitoring Well MW-1, assumed mobile concentrations. <br /> TFHG=9 ppm Benzene = 1.4 ppm- Sum of STEX-2-9 ppm <br /> Assumed average concentrations of soil and groundwater, <br /> soil <br /> Assumed soil residual saturation (highest) 5=43*,u' <br /> Retention R =S(parostty n'%)(1000 liters/meter). <br /> R z- 0.43 x 0.30 x 0.00011 pp m x .3 m3/W x 745.5 ft3 x 7.48 gal/ft = 0.00023 gal. <br /> TPI-,Gasoline <br /> R = 0.43 x 0.30 x 0.0000=4 ppm x .3 m3/ft3 x 745_5 ,W x 7.48 gal/ft = 0.000017 <br /> gal. Benzme <br /> Water <br /> C -V(n) C observed <br /> C=745.5ft= x 0.3 x 7-48gal/ftJ x 0.000009 ppm= 0.015 gal TPP Gasoline <br /> C=745.5ft1 x 0.3 x 7.48gal/ft3 x 0.0000014 ppm= 0.0023 gal Benzene <br /> parts per million ppb-parts per billion V-All STEX components <br />